SlutWalking entered the UK on Saturday with marches in Cardiff, Newcastle and Edinburgh and Glasgow. I stood under Grey's Monument in Newcastle, watching the protesters gather. As I write about SlutWalking, I first wonder if I can call the SlutWalkers "sluts", without the ironic speech marks. I think I should. Isn't this the point? To decontaminate the term through overuse? If I am repelled by repeatedly writing it – and you by reading it – perhaps we will learn whether the "reclaiming" of abusive terms is helpful, as the fight for equality stalls and porn culture swallows everything.

Grey's Monument is a phallic column, commemorating the white male Charles Grey's role in passing the Reform Act of 1832. So, as a symbol for female emancipation, it doesn't work. A first generation feminist might say we were standing under a patriarch's penis that is covered in pigeons. Some sluts, like me, are dressed in jeans or long skirts and jumpers, like Tories seeking labradors. Some wear spidery black underwear and bovver boots, like pole dancers in fear of broken glass. Others wear pink dresses and wigs and carry teddy bears. There are also some normal-looking men and a delegation from the Socialist Workers party, who for some reason don't want to give their names. They carry signs, made from cardboard or sheets. "Feminism: Back by Popular Demand." "Stop Telling Me – Don't Get Raped. Tell Men – Don't Rape." "My Clothes Aren't My Consent."

The SlutWalk is the latest chapter in the story of modern feminism, perched between the Rise of the Fragrant Good Wife – Samantha Cameron, Catherine Wales – and the Return of the Bunnies and Their Big Ears to the new Playboy club in London. The SlutWalk is not poised and it is not reticent. It is a scream of dirty, unfeminine rage ripping through conventional gender stereotypes, which seem more solid and irritating than ever.

Sonya Barnett and Heather Jarvis decided to publicise this random example of women being damned for sexual violence by a law-enforcement officer. So on 3 April, they organised the first SlutWalk. Thousands of women walked through Toronto, some with the word "slut" painted on their almost nude bodies. Their manifesto said: "We are tired of being oppressed by slut-shaming; of being judged by our sexuality and feeling unsafe as a result. Being in charge of our sexual lives should not mean that we are opening ourselves to an expectation of violence, regardless if we participate in sex for pleasure or work. No one should equate enjoying sex with attracting sexual assault."

Sanguinetti duly apologised. But, eased by Facebook and Twitter and the overuse of the term "slut", which the media adores for obvious reasons, the movement has spawned satellite SlutWalks. There were SlutWalks in Boston and Los Angeles. There will be SlutWalks in Buenos Aires and Delhi. A Facebook page says one is planned for Tehran, but I think this is a joke.

The name has caused much feminist headbanging. What is a slut? In her famous 1963 essay Sluts, Katharine Whitehorn described sluts as women who fish their clothes "back out of the dirty clothes basket because it had become, relatively, the cleaner thing," and spend their money "at the beginning of the month like drunken sailors". Then, sluts were merely disorganised women who failed the reach the polished ideal of 50s housewife serfdom – gloves on fingers, husband in secretary, Valium in mouth.

But the term slut is now sexualised to mean promiscuous woman. In using the term, some feminists believe the SlutWalkers have internalised their abuse. They march under the word "slut". They are mirrors of shame. Gail Dines wrote in the Guardian: "The term slut is so deeply rooted in the patriarchal 'madonna/whore' view of women's sexuality that it is beyond redemption." Germaine Greer disagrees, and wrote: "The rejection by women of compulsory cleansing of mind, body and soul is a necessary pre-condition of liberation . . . "

I count the sluts. There are only 30 so far. Surely more will march against the pervasiveness of rape than for the right to kill foxes? And, as I wonder if the UK SlutWalk will die in childbirth, I watch a slut munch her first victim. He is a Christian preacher in a tracksuit, wearing the sort of microphone that Cheryl Cole dribbles on. He is St John Rivers plus Sean Combs.

He is standing on a chair, talking to a small crowd. "Jesus loves you," he says in a thick Geordie accent, waving his arms. Next to him is a man advertising an Indian restaurant, and next to him is a stall informing the public about Islam. It's Saturday midday on the high street – a pick'n'mix of conflicting ideologies.

"Love the Lord," he shouts in a thick Geordie accent, "Get real with God." The slut attacks. She is slender, in jeans and bra and her head is shaved. "God doesn't give a shit," she shouts. She turns to the crowd, which is growing bigger and more interested with the promise of violence. They watch it, like TV. They take pictures and they should. This is a very photogenic movement. Bras and sluts everywhere. It could be Stringfellows, except the women don't have dead eyes. "All they do is preach shame," she screams. "This man," she points at him, "is a liar!" He sucks in his cheeks, blows out, and looks bewildered. He probably thinks she sprouted out of a Hieronymus Bosch painting. His eyes ask – why is she talking like the Bible? At me?

A bearded slut joins her. "Religion is a system of control," he screams, "a machine!" This gets applause from the crowd, even as they carry their Next bags and think about lunch. "You lying fuck!" screams the slut. "Stop your language," the preacher replies, "there are women present." "We want to live in sin!" shouts the bearded slut. I do not think this is true. I think they actually want to redesignate sin as not being sinful. Two sluts approach and kiss, very tenderly, right by the preacher. His face swells, and he gets off his chair and rubs his head. The SlutWalk has mashed the first head not its own.

The organiser (chief slut?) is Lizi Gray. She is 16 and still at school. She is small and dark, with a red rose in her hair, which makes her look like a bizarrely politicised Snow White. She makes a swift, nervous speech to the assembled crowd, who now number about 100. "Woman have the right to dress how they like and not be attacked," she says. "It has all been cleared by the police but we need to stick to the pavements." And they set off, shouting: "Whatever we wear, wherever we go, yes means yes and no means no!" People come out of shops and watch, with calm eyes. They don't clap, or jeer, or throw down their shopping bags to join us. They don't even look amazed. Even the men standing outside pubs just watch, neutrally, sipping their pints.

I chase the woman who argued with the preacher. Her name is Cleo Rose-Nash. She is a sex worker. "A week and a half ago I was raped by a client," she says. "People don't understand consent and how much rape is part of our culture. We tend not to talk about it. We tend to keep quiet about it." And so covering the SlutWalk, which began so joyously, with funny costumes and shouting at preacher-men in tracksuits until they looked as if they were going to cry, becomes the act of collecting the testimony of rape survivors. But this is a SlutWalk. Who did I think would come?

Katie Cullinane is 26; a central-casting Girl Next Door. "I was raped when I was 18," she says. "I was terrified to go to the police. I knew what they would say." And what did they say? "I was told to put it down to experience," she replies. She adds that most women are raped by people they know, and most women who are raped are wearing jeans when it happens. The stranger pouncing on a drunk woman in a thong is a lie, a symptom of our collective denial, she says. Don't blame the men. Blame the thongs, and the women who wear them.

H, 30, doesn't want to give her name. "I was sexually assaulted when I was nine," she says, "by kids at school. But I was blamed. They told me if I hadn't been on my own in a corner of the playground, it wouldn't have happened. Why should I travel in a pack?" She is dressed in jeans and a thick blue cardigan, with bright purple earrings. She came from County Durham and she has never marched for anything before. "Women should be able to go where they like, on their own, dressed however they like," she says. "Men have that right. Women should have it too. Men get drunk and they don't fear rape." She asked her mother and her partner to come with her, but they both refused.

The march is surprisingly short. Just 40 minutes, and we pause in the centre of the city. Gray thanks the SlutWalkers and the police. But a group decides to head to the Green festival in a nearby park, where I corner the SlutWalker Sarah Bennison, 37. She wears a purple kilt, a feathery cape, and pink fishnet tights under shorts, topped off with an electric-blue mohican. She looks like a human bird. That is why I noticed her. Bennison is simply marching for the right to be weird. "I am regularly called names I shouldn't be called," she says. "Slag. Slut. Tart. Freak. I quite like freak. I have had 10-year-olds asking for blowjobs at three o'clock in the afternoon. I want to be left alone to dress how I want, without being told I am stupid." She grins, and walks away.

I find the pair in pink dresses, who I call the Dorothys because they are dressed as a less drugged Baby Judy Garland. One is male and gay. The other is female and describes herself as "pan-sexual". The boy, Jordan, is 16. He is dressed in ruby slippers and a dress that says "soft cream". His hair is in pigtails. He has pink-and-white striped socks. When I tell him I thought he was a girl, he looks happy. "It [the dress] makes me one of a kind," he says, "it is who I am. If anyone has a problem with that, they can fuck themselves." He doesn't dress as a girl at school. He makes do with a bow in his hair. The Guardian photographer, who is also a Geordie, thinks Jordan is the bravest man he has ever met. "We have had a lot of abuse," says the girl, Samanteina Bloodmyer, 20, who is carrying a bright pink teddy. "Man or woman, nobody deserves to be sexually assaulted because of how they are dressed. We can brush it off, but it still angers us."

Later that night I check the Newcastle SlutWalk Facebook page and find a crisis. Vicky Vampvick Lyth has written: "I was told . . . that a small group of girls on the SlutWalk were on their way to the Green Festival . . . a police officer then said, 'You can't go there because you're dressed like a slut.' That annoyed me because it's further proof of victim blaming . . . "

I make inquiries online – what exactly was said? – but I feel stupid attempting to ask a woman on a SlutWalk who wants to reclaim the word slut how she feels when she is actually called a slut. It is still not a word that I like by itself. But at least it isn't Bunny.

• The London SlutWalk is on Saturday. Click here for other dates. Do you think SlutWalks are a useful protest against sexual assault? And what do you think of this attempt to 'reclaim' the word "slut"?